<div class="example-viewport" cdkVirtualScrollingElement>
  <div class="example-header">Content before</div>
  <cdk-virtual-scroll-viewport itemSize="50">
    <div *cdkVirtualFor="let item of items" class="example-item">{{item}}</div>
  </cdk-virtual-scroll-viewport>
  <div class="example-footer">Content after</div>
</div>
